Custom shortcuts replacing Ctrl+Tab
Go to File > User Preferences > Input, then expand the 3D View section and the "3D View (Global)" Section. It will look like this:



Scroll to the bottom and you'll see an "Add New" Button. Click that and expand the new shortcut. It will look like this:



Type in the command that Blender will need to complete when you enter your shortcut. In your case, that's: mesh.select_mode. Then Change the Action to "Enable" and set the keyboard shortcut that you want. In this case, I'll use Alt+Shift+V:



Repeat these steps for the other 3 selection modes. You can also make a shortcut to toggle sculptmode by using the command: sculpt.sculptmode_toggle You can see what these commands are by lowering the info window after you have set the mode to sculpt: